三分量VSP资料在裂缝检测中的应用

Application of three-component VSP data in fracture detection

（1. 中国石油四川石油地球物理勘探公司，四川成都610213；2.成都理工大学研究生院，四川成都610059）

Geophysical Research Center of Sichuan Geophysical Company, Chengdu 610213, China

介绍了利用纵波震源零井源距三分量VSP资料的下行横波信息对井旁裂缝进行检测的原理和实现方法。首先采用能量最大法对水平分量检波器重新定位，获得P-SV波和SH波剖面；然后采用中值滤波法将下行横波从P-SV波和SH波剖面中分离出来，并拾取下行P-SV和SH波初至，进行下行横波拉平处理，得到下行横波拉平剖面；最后在下行横波拉平剖面上取一段时窗进行快、慢横波分裂，并进行分析，确定裂缝的发育方位和裂缝密度（以快、慢横波时差表示）。实际资料处理表明，采用上述方法可以有效地确定地层裂缝的主体方位和密度，结合测井资料可以对储层进行综合分析和描述。

Theories and method of fracture detection by down- going S-wave information from zero offset three-component VSP data were introduced. Firstly, the horizontal component geophone was relocated by using the maximum energy method to obtain the P-SV and P-SH wave sections. Then the median filtering was used to extract the down-going S-wave from P-SV and P-SH wave sections and to pick the first break of down-going P-SV and P-SH wave. After that, the down-going S-wave was leveled to get leveling sections. Finally, the time window was selected from the down-going S-wave leveling sections to carry on fast and slow S-wave splitting; and then, the result was analyzed to determine the azimuth and density of fractures developed (expressed by moveout of fast and slow S-wave). Actual application shows that the method can effectively identify the main azimuth and density of formation factures and can make comprehensive analysis and description on reservoirs with logging data.